Engine starter drive



Feb. 11, 1941. Y SEKELLA Y 2,231,031

- ENGINE STARTER DRIVE Filed Oct. 6, 1938 2 Sheets-Sheet 1 Y. SEKELLA ENGINE STARTER DRIVE Filed Oct. 6, 1938 2 Sheets-Sheet 2 "un" I EEEEEFE INVENT OR.

Patented Feb. 11, 1941 UNITED STATES- ENGINE STARTER lDRIVE Youston Sekella, Elmira Heights, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application October 6, 1938, Serial No. 233,598

10 Claims.

The present invention relates to an engine starter drive more particularly to a yielding automatically"v f gaging connection between a starting motor and a member of an engine to be started. y

It is an object of the present invention to provide a novel engine starter drive which is eiiicient and reliable in `operation while being simple and economical in construction.

It is another object to provide such a device which is small and compact and of particularly short overall length as compared with previous devices of comparable capacity.V

It is a further object to provide such a device 'l5 in which traversing and yielding connections are concentrically arranged, the yielding connection surrounding the traversing connection.

It is another object to provide such a device in which the yielding connection comprises a cylindrical resilient element which is adapted to yield both compressively and torsionally during vthe transmission of torque.

It is another object to provide such a device in which the resilient element is at all times kept under initial compression by means which maintains a uniform demeshed clearance of the engine driving member.

It is another object to providesuch a device of the outboard type, in which a pinion moves away from the starting motor to engage the engine member, which is so constructed as to render unnecessary any outboard bearing or support for the outer end of the motor shaft.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a side elevation partly in section of an engine starter drive embodying a .preferred form o of the invention;

Fig. 2 is a section taken substantially on the line 2-2 of Fig. 1;

Fig. 3 is a detail in perspective partly broken s away showing the engine driving member and its traversing and driving mechanism in disassembled relation;

Fig. 4 is a view similar to Fig. 1 of an embodiment ofthe invention in which -the pinion moves w toward the starting motor in engaging the engine gear? Fig. 5 is a view similar to Fig. 4 of a similar embodiment of the invention employing a coiled spring for the yielding element; Fig. 6 is a cross-sectional view of the structure illustrated in Fig. 4 taken substantially on the line 6-6 thereof; and

Fig. 7 is a' cross-sectional view of the structure illustrated in Fig. 5 taken substantially on the line 1-1 thereof.

In Fig. 1 of the drawings there is illustrated a starting motor I having a power shaft in the form of an extended armature shaft 2 on which a screw shaft 3 is xedly mounted as by means of a key 4 and set screw 5. An engine driving l0 member in the form of a pinion member 6 is slidably journalled on the power shaft 2 for movement into and out of engagement with a member -such as a flywheel gear 'l of an engine to be started. l l5 Means for automatically traversing and rotating the pinion 6 from the screwshaft 3 are provided comprising a nut member 8 mounted on the screw shaft'3, a barrel member 9 surrounding the nut and screw shaft, and an abut- 20 ment member II fixed in the end of the barrel in any suitable way as indicated at I2, and rigidly connected as by welding or brazing as indicated at I3 to an extended hub I4 of the pinion 6. Means are 4provided for yieldingly connecting the 25 nut 8 and barrel 9 in the form of a cylindrical block I5 of elastically deformable material such as rubbersurrounding the nut 8 within the barrel 9 and bearing at-one end against a circular ange I6 formed on or fixed in any suitable man- 3o ner as by welding or brazing adjacent one end of the .nut 9, and bearing at its other end on an annular plate I1 fixed as indicated at I8 in the free end of the barrel 9. Thimbles I9 and 2| located in reversed relation adjacent the ends of 35 the yielding member I5, are preferably employed to complete the enclosure of the yielding member and prevent localized wear thereof. n

The expansion of the yielding member I5 is limited by the engagement of the end of nut 8 40 against the abutment member I I, and the operative position of the pinion member`6 is dened by the abutment of the end of the pinion hub I4 and the abutment member II against the end of the screw shaft 3. Means are 'provided f or 45 normally maintaining the pinion 6 in its idle position as illustrated in the form of an antidrift spring 22 located on the power shaft 2 between the pinion hub and screw shaft and preferably seated in a recess 23 in the screw shaft. 50

In order to prevent rebounding of the pinion and associated parts toward the iiywheel after being demeshed therefrom, the nut 3 is provided with a smooth counterbore 24 which permits the nut to run off the end of the threads of the 55 screw shaft 3 and thereby permit the pinion to overrun the power shaftl 2. Means are provided for assuring initial re-engagement of the threads of the screw shaft and nut in the form of a reentry spring 25 housed in a thimble 25 anchored in the annular plate I1, said spring bearing against a thrust ring 21 mounted on the screw shaft in abutting relation with the ends of the threads thereof.

In the operation of this embodiment of the invention, actuation of the power shaft 2 in the direction of; the arrow causes the nut 8 to thread itself on the screw shaft 3, thus drawing the vpinion 6 into mesh with the engine gear 1 through the intermediary of the ange I6, yielding member I5, plate I1, barrel 9, abutment member II and pinion hub I4. When the pinion hub and abutment member engage the end of the screw shaft 3, further longitudinal movement is prevented and rotation of the screw shaft 3 is transmitted to the pinion 5 through the yielding driving connection formed by the compression and torsion of the elastic element I5.A

When the engine starts, the acceleration of the pinion 5 bythe engine gear 1 causes it to overrun the power shaft 2 whereby the pinion and associated parts are moved back to their idle positions by the unscrewing of the nut 8 from the screw shaft 3, after which said parts are permitted to overrun freely until their momentum is dissipated.

If, during the meshing operation, a tooth of the pinion 5 abuts against a tooth of the engine gear, the compressive elasticity of the member I5 permits the nut 8 to move longitudinally while building up suiiicient torque in the threaded connection to index the pinion into proper registry, after, which the expansion of the member I5 snaps the pinion into initial mesh, and the meshing and cranking operation thereupon takes place in the usual manner.-

. In Fig. 4 there is illustrated an embodiment of the invention-of the inboard meshing type arranged to effect further reductions in space requirements of the drive. As there shown, a power shaft 3| is provided having a smooth portion 32, a splined portion 33 and a reduced smooth portion 34 adjacent thereto. An engine driving member in the form of a pinion 35 is slidably journalled on the first-mentioned smooth portion of the power shaft 3| for longitudinal movement into and out of engagement with a member such as a flywheel gear 35 of an engine to be started. A screw shaft 31 is splined on the portion 33 of the power shaft, and a sleeve 38 fixed to the screwy shaft 31 in any suitable way as Aby welding or brazing as indicated at 39, is anchored to the power shaft by means such as a pin 4|.

A nut member 42 is mounted on the screw shaft 31 and has a. radial ange 43 formed thereon or suitably fixed thereto'as indicated at 44. A barrel member 45 suitably fixed to the pinion 35 as indicated at 45 is arranged to surround the screw shaft and nut andy is provided with an abutment member 41 fixed in. the free end thereof as indicated at 48. A yielding driving connection between the nutand barrel is provided in the form of a cylindrical block 49 of elastica]- ly deformable material surrounding the nut 42 within the barrel and bearing against the ange 43 thereof so as to normally hold itin engagement with the abutment member 41.

. The nut 42 is counterbored as indicated at 5| in order to allow the nut to run oil the threads of the screw shaft when the pinion 35 overruns the power shaft 3|. A re-entry spring 52 is located between the pinion 35 and screw shaft 31 to insure initial re-engagement of the threads on the nut and screw shaft. The pinion 35 is normally maintained in idle position by an antidrift spring 53 located between the screw shaft and the abutment member 41, and preferably seated in a recess 54 in the end of the screw shaft.

In the operation of this embodiment of the invention, rotation of the power shaft 3| in the direction ofthe arrow causes the nut 42 to thread itself along the screw shaft 31, pushing the pinion 35 into mesh with the ring gear 35 by means of the yielding member 49. The meshing movement of the pinion is limited by the engagement of the abutment member 41 with the adjacent end of the screw shaft 31, after which rotation of the screw shaft is transmitted to the pinion, the transmission of vtorque being cushioned by the compression and torsion of the yielding member 49. In order to enclose and prevent localized stresses in the member 49, sheet metal thimblesli and 56 are preferably provided, bridging the spaces between the barrel, nut member and flange 43: Thimble 56 is shown welded or brazed to the flange 43, which arrangement has sometimes been found preferable to the loose mounting arrangement of thimble I9 in Fig. l.

In the embodiment of the invention illustrated in Fig. 5, the structure is substantially the same as in-Fig. 4 with the exception that a coiled spring 51 is substituted for the yielding member 49 in Eig. 4. 'I'he spring 51 is anchored at its ends to the barrel and nut respectively, such anchorage being here illustrated in the form of outturned ends 58 and 59 of the spring engaging in openings 5| and 52 in the barrel 45 and flange 43 respectively.

Since the remaining elements of the structure are substantially similar to those in Fig. 4 and are similarly designated, further description thereof is deemed unnecessary.

In the operation of this embodiment of the invention, meshing of the pinion 35 with the ring gear 35 is brought about by rotation of the power shaft 3| as previously set forth. When the abutment member 41 engages the end of the screw shaft 31, the nut 42 continues to travel forward, compressing the spring 51 until the convolutions thereof are pressed tightly together. The longitudinal movement of the nut with respect to the barrel may be limited by the lengththe spring 51 and by the friction set up by the compression of the parts.

When the engine starts, release and overrunning of the drive take place as previously described.

It will -be' appreciated that there is here provided an engine starter drive which by reason of the concentric telescopic arrangement of the parts is of very short overall length, and since the yielding element is subjected to both compression and torsion while being completely supported and protected 'from localized stresses, the radial dimensions of the drive and in particular of the yielding element may also be reduced. It

' parting `ient material surrounding Although certain embodiments of the invention have been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made in the design and arrangement of the parts withoutvdefrom the spirit of the invention as defined in the claims appended hereto.

What is claimed is: 4

l. In an engine starter drive, a power shaft, a screw shaft fixed thereto, a pinion member slidably journalled on the power shaft for movement into and out of engagement with a member of an engine to bestarted, thrust means for the pinion arranged to abut the end of the screw shaft when' the pinion is in operative position, a nut threaded on the screw shaft, a barrel member surrounding the nut and non-rotatably connected to the thrust mean-s vand pinion, and

means including a cylindrical member of resilthe nuty in the barrel and yieldingly connecting the nut to the barrel.

2. In an engine starter drive, a power shaft, a screw shaft fixed thereto, a pinion member slidably journalled on the power shaft for movement into and out of engagement with a member of an engine to be started, thrust means for the pinion arranged to abut the end of the screw shaft when the pinion is in operative position, a nut threaded on the screw shaft, a barrel member surrounding the nut and non-rotatably anchored to the, thrust means and pinion, and a cylindrical member of resilient material surrounding the nut in the barrel, said nut and barrel having means for compressing said resilient member -by longitudinal movement of the nut after the thrust means engages the end of the screw shaft.

3. In an engine starter drive, a power shaft, a screw shaft fixed thereto, a pinion member slidably journalled on the power shaft for movement into and out of engagement with a member of an engine to be started, thrust means for the pinion arranged to abut the end of the screw shaft when the pinion is in operative position, a nut threaded on the screw shaft, a barrel member surrounding the nut and non-rotatably anchored to the thrust means and pinion, and yielding means including a cylindrical block of resiliently deformable material surrounding the nut in the barrel and forming the sole driving connection between the nut and the barrel.

4. In an engine starter drive, a screw shaft. a nut threaded thereon, a cylindrical resilient transmission member surrounding the nut and connected at one end thereto, a barrel surrounding the nut and transmission member and connected at one end to the free end of the transmission member, an engine driving member connected to the other end of'the barrel, and an abutment member non-rotatably anchored in the barrel confining the nut and transmission member in the barrel and adapted to come into engagement with the end of the screw shaft when the parts are in operative position.

5. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a nut threaded on 75 the screw shaft, an engine driving member on `the power shaft coaxial with the nutyand means including a barrel surrounding the nut and a resilient element within the barrel for transmitting rotation and longitudinal movement from the nut to the engine driving member, said means also including' an abutment member non-rotatably connected to the barrel serving'toconne the nut therein and limit the expansion of the lresilient element, said abutment member being arranged to engage the end of the screw shaft when the engine driving member is in operative position to thereby, limit the longitudinal movei ment of the parts.

6` In an engine starter drive, a power shaft, a screw shaftxed thereon, a. pinion journalled on the power shaft and slidable thereon into and out of engagement with a member of the engine to be started, a nut threaded on the screw shaft having a radial ange, a block of elastically deformable material encircling the nut and abutting said flange, and a barrel member non-rotatablyv anchored to the pinion enclosing the nut and block and having a flange abutting said block operative when the power shaft is actuated to move the pinion into engagement with the engine member, said pinion having means abutting the screw shaft to limit the engaging movement of the pinion.

'7. In an engine starter drive, a power shaft,V

- to move the pinion into engagement with the engine member, said nut being arranged to run oil? the threads of the screw shaft when the pinion is returned to idle position, and means including a spring and operative to urge the nut into initial engagement with the threads on the screw shaft.

8. In an engine-starter drive, a power shaft, a screwvshaft xed thereon, a nut threaded on the screw shaft, an engine driving member slidably journalled on the power shaft, a barrel enclosing the screw shaft and nut non-rotatably connected at one end to the engine driving mem, ber, an abutment member non-rotatably. connected in the other end of the barrel and arranged to engage the end of the screw shaft when the engine engaging member is in operative position, and a.A resilient connection transmitting longitudinal movement and rotation from the nut to the engine driving member.

9. In an engine starter drive, a power shaft, a screw shaft xed thereon, a nut threaded on the screw shaft, an engine driving member slidably journalled on the power shaft, a barrel enclosing the screw shaft and nut non-rotatably connected at one end to the engine driving member, an abutment member non-rotatably conn ected in the other end of the barrel and arranged to` engage the end of the screw shaft when the engine engaging4 member is in operative position, and a cylindrical elastic transmission member surrounding the nut and connected at its ends to the nut and barrel.

10. In an engine starter drive, a power shaft, a screw shaft xed thereon, a nut threaded on the screw shaft, an engine driving member slidably journalled on the power shaft, a barrel en- 75` sion member` surrounding the nut and compressively connected at its ends to the nut and barrel, said abutment member being arranged to engage the nut when in idle position and limit the eX-.v

pansion of the transmission member.

YOUSTON SEMILLA. 

